Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/3842—Manufacturing moulds, e.g. shaping the mould surface by machining
  • B29C33/3857—Manufacturing moulds, e.g. shaping the mould surface by machining by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
  • B29C70/342—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
  • B29C70/549—Details of caul plates, e.g. materials or shape
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
  • B29C43/12—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using bags surrounding the moulding material or using membranes contacting the moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2063/00—Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
  • B29K2105/08—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts of continuous length, e.g. cords, rovings, mats, fabrics, strands or yarns
  • B29K2105/0809—Fabrics
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2863/00—Use of EP, i.e. epoxy resins or derivatives thereof as mould material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/757—Moulds, cores, dies

Definitions

• This invention pertains generally to producing facsimiles of physical objects, and more particularly to production of a facsimile with uniform wall thickness and surface topography which matches that of a production stage component.
• Facsimile 10 represents a facsimile produced using conventional techniques.
• Lower surface 12 represents the front side of a facsimile 10 which was fabricated from a master model identical to master model 16 shown in FIG. 1.
• Surface 12 is the surface of facsimile 10 which was immediately adjacent to the surface 22 of master model 16 and, as can be seen, complements the surface topography of master model 16.
• Upper surface 14 represents the back side of facsimile 10 to which pressure was applied. Note that the topography of surface 14 does not conform to the shape of surface 12 and that facsimile 10 does not exhibit uniform wall thickness.
• a process of producing facsimiles of physical objects comprising the steps of: placing a fibrous material over the surface of a master model to be duplicated; impregnating the fibrous material with a thermosetting resin; placing a pressure pad over the fibrous material, the pressure pad having a first side and a second side, the first side having surface topography substantially complementing the surface topography of the master model, the second side adapted for substantially uniform transmittal of pressure from the second side to the first side; applying pressure to the pressure pad; curing the resin impregnated fibrous material; and removing the cured resin impregnated fibrous material from the surface of the master model, the cured resin impregnated fiber having a substantially uniform wall thickness.
• the present invention pertains to a process for producir j a dimensionally accurate carbon fiber facsimile of a production stage component, typically a sheet metal or plastic component.
• the carbon fiber facsimile produced by the present invention is a dimensionally accurate reproduction of that component and will have uniform wall thickness as well as a degree of rigidity equal to or greater than that of the actual production part. Facsimiles produced by the present invention are particularly useful for simulation of sheet metal and plastic parts used in the construction of automobile inner chassis and outer body assemblies.
• the process of the present invention generally begins with the preparation of a pressure pad which is used to provide back-side definition to the facsimile produced.
• a parting agent is applied to the surface area of a dimensionally approved master model to be duplicated.
• a surface coat of epoxy is then applied to the surface of the master model, several layers of fiberglass weave skin are laminated over the surface of the master model with coats of epoxy applied between the layers, a final coat of epoxy is applied to the upper surface of the layers of fiberglass weave skin, and the laminated material is cured.
• the pressure pad is molded from the recessed areas (fillets) of the master model after first applying a layer of sheet wax equal in thickness to the thickness of the facsimile to be produced. Using either alternative, the pressure pad is removed from the master model when the curing process is complete.
• the front side of the pressure pad will have a surface topography which substantially complements the surface topography of the master model to be duplicated.
• the front side of the pressure pad complements the surface topography of the master model except to the extent that it was displaced from the actual surface of the master model by the layer of sheet wax, since the layer of sheet wax has is same thickness as the facsimile to be produced.
• the back side of the pressure pad is then adapted by filling and rounding out any recesses that exist so as to leave only shallow gently curved areas of female radii, or fillets.
• This filling and rounding out of the recesses in the back side of the pressure pad is a critical step in the entire process because it permits pressure applied to the back side of the pressure pad to be uniformly transmitted to the front side of the pressure pad, and is a step required to overcome the failures of conventional facsimile techniques. All sharp and deep recesses in the back side of the pressure pad are eliminated in this manner.
• the skin is cut into separate members or, alternatively, holes or slots are cut in the skin for excess epoxy to flow through.
• the pressure pad was formed from only the fillet areas of the master model, sheets of wax or laminate strips are used as pad members to cover the remaining surface areas of the master model.
• the master model is cleaned and coated with a parting agent. A coating of epoxy is then brushed on over the parting agent, and sheets of woven material made from carbon fiber, fiberglass, Kevlar, or a combination of thereof, are placed over the epoxy, using a sufficient number of layers to achieve the desired wall thickness of the facsimile to be fabricated.
• the woven material is made from carbon fiber.
• the sheets of carbon fiber material are laminated by coating them with epoxy.
• Other thermosetting resins such as polyester could be used, but epoxy is recommended for providing the best stability.
• the pressure pad is then coated with a parting agent and placed over the epoxy impregnated carbon fiber material, the pad members being separated or slotted so as to leave gaps through which excess epoxy can flow.
• a breather cloth which will absorb excess epoxy is placed over the pressure pad.
• a deformable rubber or plastic membrane is placed over the breather cxoth.
• Pressure is then applied over the entire surface of the deformable membrane and the material is cured.
• subatmospheric pressure vacuum
• the pressure can also be positive atmospheric pressure or physically applied with a clamping means.
• the deformable membrane, breather cloth and pressure pad are stripped off, the carbon fiber facsimile is removed from the master model, and the edges are trimmed as necessary.
• the backside definition which results from use of a pressure pad produces a facsimile which has a uniform wall thickness.
• the deformable membrane stretches into and presses against the entire back surface of the pressure pad. Because the front side of the pressure pad had a surface topography substantially complementing the surface topography of the master model, the back side of the facsimile will have similar definition.
• the resultant product is a dimensionally accurate carbon fiber facsimile of the production component.
• Automotive inner and outer chassis applications include proof out of manual and computer aided design details, coordination of assemblies before fabrication of prototype and production tools, matching of connecting and/or mounting flanges, elimination of design interference, center of gravity determinations of assemblies, torsional rigidity studies, packaging studies of assemblies, early coordination of welding machines and fixtures, assistance and coordination of robotics and transfer machines, and correlation aids for checking fixtures.
• Automotive interior applications include proof out of manual and computer aided design details, complete interior environmental quality fixtures (macrobucs) , correlation aids for process gauges, pre- prototype assemblies, and interiors for clinic cars.
• Another object of the invention is to produce facsimiles which have uniform wall thickness.
• Another object of the invention is to produce facsimiles which identically duplicate production components.
• Another object of the invention is to produce facsimiles with rigidity equal to or greater than that of the actual production part under ambient temperatures prevailing during tooling and assembly.
• Another object of the invention is to achieve repeatability in properties such as rigidity and specific weight.
• FIG. 1 is a cross-sectional view of a master model used in the process of the present invention.
• FIG. 2 is a cross-sectional view of the lay-up resulting from the steps employed to prepare a pressure pad from the master model shown in FIG. 1.
• FIG. 3 is a cross-sectional view of the pressure pad of FIG. 2 showing multiple layers of woven pressure pad material.
• FIG. 4 is a cross-sectional view of the lay-up resulting from the steps employed to prepare a carbon fiber facsimile using the master model shown in FIG. 1 and the pressure pad shown in FIG. 3.
• FIG. 5 is a cross-sectional view of the carbon fiber facsimile of FIG. 4 showing multiple layers of woven facsimile material.
• FIG. 6 is an exploded view of FIG. 4.
• FIG. 7 is a cross-sectional view of an exemplary carbon fiber facsimile produced from the master model shown in FIG. 1 using the process of the present invention.
• FIG. 8 is a cross-sectional view of an exemplary carbon fiber facsimile produced from the master model shown in FIG. 1 using conventional means.
• the process begins with the preparation of a dimensionally accurate master model 16 from which facsimile 20 shown in FIG. 7 will be produced.
• Master model 16 will have a surface topography 22 which is complementary to one surface of the facsimile to be produced.
• Master model 16 is called a "negative master” since the facsimile produced fits within master model 16. If a mirror image of master model 16 was used instead, then the master model would be a "positive master.”
• the selection of a positive or negative master model depends primarily on the shape of the facsimile to be produced and whether the surface topography of the master model is to represent the inside or outside of the production stage component.
• Master model 16 can be fashioned satisfactorily from a number of materials. Examples are solid wood, laminated wood, epoxy or urethane model plank such as CibaGeigy Corporation "Oreol", epoxy/fiberglass laminations, epoxy/carbon laminations, plaster casts, solid metal, spray metal, fiberglass reinforced or unreinforced cardboard models, or high density urethane, styrene, or acryl foam. Because the process of the present invention requires application of pressure to master model 16, the material from which master model 16 must be constructed to retain the required dimensional accuracy and not fatigue under pressure. The best suited material is model plank which is in common use in the industry.
• thermosetting resins which will adhere to surface 22 of master model 16, to prevent adhesion of these thermosetting resins it is desirable to apply a parting agent 24 to surface 22 of master model 16, as well as to the surface of any reusable component which will be in contact with thermosetting resin.
• acceptable compounds for parting agent 24 are polyvinyl alcohol or silicone in combination with wax.
• the components used in the present invention could be made of materials which do not adhere to the thermosetting resin.
• pressure pad 26 can be formed directly from surface 22 of master model 16 as a continuous skin. In other applications, preparation of pressure pad 26 requires intermediate steps in the process. For a complicated surface topography, such as shown in master model 16, the forming pressure pad 26 directly from surface 22 of master model 16 would produce a pressure pad which would not fit into place after the material from which the facsimile will be fabricated is later applied to master model 16. This problem occurs when vertical or near vertical walls are adjacent to recessed areas such as those adjacent to fillet 18.
• the first step is to place a layer of sheet wax 30 over the recessed portions of surface 22 of master model 16 as shown.
• the thickness of sheet wax 30 should be the same as that of the facsimile to be produced in order to produce a proper fit.
• An example of suitable sheet wax is Master Brand available from Kondt-Collins Co.
• a coat of parting agent 24 is then applied to the surface of the sheet wax 30 and the remaining portions of surface 22 not covered by sheet wax 30 to prevent adhesion of thermosetting resin to those surfaces.
• a surface coat of thermosetting resin 28 is then applied over the coat of parting agent.
• thermosetting resin Layers of woven fiberglass or carbon fiber pad material 32, or the like, are then laminated over the surface coat of thermosetting resin to form pressure pad 26.
• Woven material is used so that the thermosetting resin will penetrate the material between the weaves and form a matrix.
• a final coat of thermosetting resin 34 is then applied over the top layer of woven material, and the layers of laminated woven material are pressed into place over the surface of the master model. The thermosetting resin is then cured and the pressure pad is removed from the master model.
• pressure pad 26 is created at break point 36 because sheet wax 30 was not applied over a portion of surface 22. Despite this discontinuity, pressure pad 26 is still formed in a continuous piece by bending the layers of woven pad material 32 downward around break point 36.
• sheet wax 30 can be omitted.
• a layer of parting agent is applied to the entire surface of the master model before applying a surface coat of thermosetting resin, and the layers of woven fiberglass or carbon fiber material are laminated in place as generally described above. These steps are generally suitable for preparation of a pressure pad where the surface topography of the master model does not contain vertical or near vertical walls adjacent to recessed areas.
• a pressure pad could be formed by molding the woven fiberglass or carbon fiber material only into recessed areas such as fillet 18 and immediately adjacent areas, and using sheet wax as the remaining portions of the pressure pad.
• pressure pad 26 is formed from master model 16 in this manner, the lower or front surface of pressure pad 26 will have a topography which is substantially complementary to the topography of surface 22, except to the extent that it was displaced from surface 22 by sheet wax 30. Where the use of sheet wax 30 is not required, the front surface of pressure pad 26 will be an identical reverse image of surface 22 of master model 16. It is critical in the process that the topography of one surface of pressure pad 26 substantially complement the topography of surface 22 of master model 16.
• the next step is to adapt the upper or back surface of pressure pad 26 so that pressure applied to the back surface will be uniformly distributed to its lower or front surface. This is done by filling in and rounding any depressions 38 on the back surface of pressure pad 26 with epoxy or the like so as to create a relatively shallow fillet 40 with gentle curves as shown.
• Pressure pad 26 is then removed from master model 16 and separated into pad members 42, 44 by making a vertical cut or otherwise detaching pad members 42, 44 at or near break point 36. Separation of these pad members is unnecessary when the pressure pad is formed directly from the surface of the master model.
• Pressure pad 26 is now ready to use. Referring now to FIG. 1, FIG. 4, and FIG. 5, surface 22 of master model 16 is then cleaned and a coat of parting agent 24 applied to surface 22 as before to prevent adhesion of thermosetting resin. Next, a surface coat of thermosetting resin 50 applied over the coat of parting agent.
• Layers of woven facsimile material 52 are then laminated over the surface coat of thermosetting resin with coats of thermosetting resin applied between the layers, to form the continuous laminated skin that will become facsimile 20.
• Woven material is used so that the thermosetting resin will penetrate the material between the weaves and form a matrix.
• the woven facsimile material 52 can be sheets of glass fiber, carbon fiber, aramid fiber, Dupont's Kevlar fibers, and the like, or any combination of those materials.
• the weave can be unidirectional or bidirectional, but must be open so as to permit the thermosetting resin to form a matrix.
• the number of layers of woven facsimile material 52 used is determined by the wall thickness of the facsimile to be produced, the wall thickness being the same as the production stage component.
• Suitable facsimile material employing graphite or carbon fibers is available from numerous commercial sources, such as Hercules, Morganite, Stackpole, Union Carbide, and others. Textile Technology produces a particularly suitable graphite cloth with an open weave under the designation Yarn 3K #G104.
• any advanced exotic, synthetic or natural fiber suitable for impregnation and bonding by a thermosetting single or multicomponent matrix could be used for facsimile material 52.
• thermosetting resin 54 is applied over the top layer of facsimile material 52.
• the surfaces of pressure pad 26 are then coated with the same parting agent as was applied to surface 22 of master model 16.
• Pressure pad 26 is then pressed into place over facsimile material 52 leaving gap 46 between pad members 42, 44. Gap 46 is important so that excess thermosetting resin can escape through the opening created thereby when pressure is applied.
• pressure pad 26 can alternatively be cut into strips, or holes or slots 48 can be cut into pressure pad 26 at other locations so that excess thermosetting resin can escape if necessary.
• a strip of sheet wax could be used in its place. As described earlier, sheet wax is also a suitable pressure pad material, particularly in relatively horizontal areas.
• breather cloth 56 which is a conventional cloth material or teflon-coated glass cloth capable of absorbing excess thermosetting resin is placed over pressure pad 26.
• Deformable rubber membrane 58 is then placed over breather cloth 56.
• the deformation characteristics of rubber membrane 56 are not critical so long as it stretches easily and will not rupture under pressure or vacuum. Deformable plastic could also be used instead of rubber.
• the nested assembly is subjected to pressure and the resin impregnated facsimile material 52 is cured to form facsimile 20.
• thermosetting resin penetrates the weave in facsimile material 52 and hardens.
• the pressure is subatmospheric (e.g., vacuum at approximately thirty inches mercury) and can be applied in a vacuum chamber or conventional vacuum bag. Clamping pressure or positive atmospheric pressure can also be satisfactorily used.
• thermosetting resin used to laminate facsimile material 52, as well as to laminate pad material 32 can be from the family of liquid polymers and liquified polymers, and includes epoxy, urethane, and polyester.
• thermosetting epoxy resin is WB 400 available from Resin Services and can be used with the WH 150 hardener (catalyst) available from the same source.
• Another suitable epoxy is available from CibaGeigy Corporation as MY-720.
• Other thermosetting matrices such as etton, modar, or any other matrix from the family of liquid polymers and liquified polymers capable of penetrating, or whetting, facsimile material 52, and which will subsequently cure to a hardened or semi-hardened state, would also be suitable.
• thermosetting resin is used with a catalyst for generation of exothermic heat by the chemical reaction which results.
• Curing time can be one to twelve hours depending upon the particular thermosetting resin used.
• Facsimile material 52 can also be a pre-preg material but will require the application of external heat.
• pre-preg is a term of art denoting preimpregnated unidirectional or bidirectional continuous filament fiber materials that may be temperature cured to provide a rigid composite material.
• a typical prepreg which can be used is Hercules Incorporated•s magnamite prepreg-type 3501-AS. This is a graphite fiber epoxy and employs a thermosetting resin matrix that cures at approximately 350 degrees for a period of 30 minutes.
• Facsimile 20 has two surfaces, a lower or front surface 60 which has a topography which complements the topography of surface 22 of master model 16, and an upper or back surface 62 whic has a topography which is substantially parallel to th topography of surface 22 of master model 16.
• This fron and back definition is achievable only by the use o pressure pad 26, and the manner in which the back side o pressure pad 26 is adapted so that pressure applied to the back side will be uniformly transmitted to the front side of pressure pad 26.
• fillet 40 in the back side of pressure pad 26 is the basis of uniform pressure transmittal.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Manufacturing & Machinery (AREA)
• Moulding By Coating Moulds (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Carbon And Carbon Compounds (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (1)

Publications (2)

Family

ID=1239616

Family Applications (1)

Country Status (6)

Families Citing this family (1)

Family Cites Families (1)

• 1991
  • 1991-12-19 CA CA002101545A patent/CA2101545C/en not_active Expired - Fee Related
  • 1991-12-19 DE DE69124706T patent/DE69124706T2/de not_active Expired - Fee Related
  • 1991-12-19 JP JP4503395A patent/JP2533725B2/ja not_active Expired - Lifetime
  • 1991-12-19 EP EP92903401A patent/EP0580586B1/de not_active Expired - Lifetime
  • 1991-12-19 AT AT92903401T patent/ATE148851T1/de not_active IP Right Cessation
  • 1991-12-19 WO PCT/US1991/009636 patent/WO1993011922A1/en active IP Right Grant

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events